Mountain rescue teams from RAF Lossiemouth, RAF Leeming and Torridon are working with the Search and Rescue Dogs Association (SARDA) and a coastguard search and rescue helicopter are combing the area on Tuesday.

Police are appealing for anyone who stayed in bothies in the area over the weekend to contact them.

Sergeant Bruce Crawford said: “As time passes we are naturally increasingly concerned for Mr Mitchell’s wellbeing and I would ask anybody who thinks they have seen him or someone matching his description to contact us.

“We have heard from a number of other walkers who were in this area at the weekend and we’re grateful for all of the information we have received.

“Mr Mitchell intended to stay in bothies during his walk. We know from guest books from the bothies in the area that there were other walkers who stayed there over the weekend who we have yet to hear from.

“I would ask that these people get in touch. Any information or possible sightings, even if it was something you thought was inconsequential at the time, could help us in our search.”